Incandescent lamps having a transport gas comprising a bromine and a chlorine hydrocarbon compound

ABSTRACT

A regenerative cycle electric incandescent lamp having a tungsten filament and containing a transport gas essentially consisting of an inert gas and a bromine and chlorine hydrocarbon compound.

mite States Patent [72] Inventors Riksterus Auguste Johannes MariaMeijer;

Appl. No. Filed Patented Assignee Priority Germin Remi TJampens, hoth o1Emmasingel, Eindhoven, Netherlands 838,781

July 3, 1969 Division 01 Ser. No. 672.619. Oct. 3. 1967. Pat. No.3.484.146.

June 22, 1971 11.5. Phillips Corporation New York, NY.

Oct. 8, 1966 Netherlands INCANDESCENT LAMPS HAVING A TRANSPORT GASCOMPRISING A BROMINE AND A CHLORINE HYDROCARBON COMPOUND 4 Claims, 2Drawing Figs.

[52] US. Cl 313/174, 313/176, 313/222, 313/223 [51] Int. Cl H0lk1/50[50] Field of Search 313/174, 176, 179, 185, 222, 223

[56] References Cited UNITED STATES PATENTS 1,925,857 9/1933 Van Liempt313/223 X 3,418,512 12/1968 TJampens eta]. 313/222X PrimaryExaminer-Raymond F. l-lossfeld Attorney-Frank R. Trifari ABSTRACT: Aregenerative cycle electric incandescent lamp having a tungsten filamentand containing a transport gas essentially consisting of an inert gasand a bromine and chlorine hydrocarbon compound.

PATENTEH'JUN22 mm FIG] FIG.2

INVENTOR5. RIKSTERUS A.J.M. MEIJER GERMIN R. T'JAMPENS BY i '6 I? AGENTllNCANDESCENT LAMPS HAVING A TRANSPORT GAS COMPRISING A BROMINE AND ACHLORINE HYDROCARBON COMPOUND This is a division of applicants copendingpatent application, Ser. No. 672,619, filed Oct. 3, 1967, now US. Pat.No. 3,484,146.

A method of manufacturing incandescent lamps having a tungsten filamentin which during the final stage of manufacture the lamp is evacuated andfilled with a mixture of an inert gas and bromine-chlorine hydrocarbons.

The invention relates to a method of manufacturing an incandescent lamphaving a filament of tungsten and a brominecontaining transport gas inwhich during the last manufacturing steps the lamp is evacuated, is thenconnected to a storage cylinder which contains an inert gas and abromine-hydrocarbon compound, is then filled with the gas mixture to thedesired pressure and subsequently closed, usually by sealing an exhausttube which up to that instant formed one assembly with the bulb.

The bulbs of incandescent lamps obtained in this manner remain brighttill the end of the lifetime of the tungsten coil providedit is ensuredthat the wall of the bulb during operation of the lamp everywherereaches a temperature at which the tungsten-bromine compounds formed inthe lamp cannot condense. After some time in operation there prevails adynamic equilibrium in the lamp in which as a result of thermaldecomposition of the tungsten compound in the proximity of the coil theamounts of deposited tungsten and evaporated tungsten are the same.

Suitable bromine-hydrocarbons are, for example, tribrornomethane (CHBrmonobromomethane (CH Br) but in particular the dibromomethane (CI-I,Br,)Other brominehydrocarbon compounds also, if required together with asuitable amount of hydrogen, may be used.

Dibromomethane, which is preferably used has a rather low vapor pressureat room temperature. This is a drawback in this particular way of lampmanufacturing. At 25 C. this pressure is only approximately 40 Torr.

For practical reasons the partial pressure of the dibromomethane in thestorage cylinders may not be equal to said vapor pressure. In fact, itshould be prevented that as a result of a decrease in temperaturecondensation of the dibromomethane occurs in the storage cylinders. Adecrease in temperature may occur, for example, at night or during theweekend. Condensation results in unfavorable variation of thecomposition of the gas mixture in the storage cylinder. After anincrease in temperature it takes ample time until a homogeneous gasmixture is present again in a cylinder in which condensation hasoccurred, For that reason the storage cylinders are normally filled withdibromomethane to a partial pressure of approximately 28 Torr whichcorresponds to the pressure of said compound at approximately 16 C.

in practice this means, that, taking losses into account, for exampleapproximately 10.000 lamps with a volume of approximately 0.25 cm. canbe filled to a pressure of approximately 5 atmospheres from a cylinderhaving a capacity of 8 l. which is filled with a gas mixture of kryptonl. dibromomethane to a pressure of 8.2 atmosphere.

in this case the storage cylinder may be used until the pressure thereinhas decreased to approximately 1.2 atmosphere. The cylinder is thenemptied, so many litres of krypton of 1.2 atmosphere being lost as thewater capacity of the cylinder is. it is not possible to replenish acylinder in which a pressure of 1.2 atmosphere prevails within areasonable time with a mix ture of krypton and CH,Br 2 because the vaporpressure of the latter is too low for that purpose. The operation offilling the lamps must thus be interrupted for exchanging the storagecylinders in this example after every approximately 10.000 lamps.

it is the object of the invention to mitigate these drawbacks and aparticular object of the invention is to enable the filling of morelamps using one storage cylinder, to restrict the loss of rare gas, andto reduce the number of times a new gas mixture has to be prepared andstored in storage cylinders.

According to the invention this may be achieved by using a gas mixturein which bromine and chlorine are present in the form of hydrocarboncompounds.

The greatest improvement is reached if bromochloromethane (CH BrCl) isused. In comparable circumstances the admissible partial pressure ofthis compound in the storage cylinders is approximately Torr. This meansthat with one storage cylinder filled with bromochloromethane to saidpressure, if also the partial pressure of the inert gas is adaptedaccordingly, approximately three times as many lamps can be filled withthe same halogen percentage as is possible with bromomethane in themanner described.

in this manner the loss of rare gas decreases to approximately one thirdwhile the labour time for'exchanging, filling and the like can bereduces to one third.

However, a considerable saving is also obtained already if the gasmixture contains both dibromomethane and dichloromethane to the samepartial pressure. From one storage cylinder approximately two times asmany lamps can now be filled, while the labour time for certain parts ofthe manufacturing process can approximately be halved, too.

The invention is based on the use of the property that the mixedbromine-chlorine hydrocarbon compounds and the chlorine hydrocarboncompounds generally have a higher volatility than the correspondingbromine hydrocarbon compounds.

It was found that in lamps which contain a bromine containing transportgas, for example, half of the bromine may be replaced by chlorine; withthis composition in which the ratio bromine-chlorine is H additionaladvantages are obtained. The ratio hydrogen to halogen preferably islikewise lzi in gramatoms.

It was found that when using such a ratio the total quantity of halogen(bromine together with chlorine) in gramatoms in the lamps may besmaller than in the case of bromine alone, with an equal lifetime andluminous efiiciency of the lamps.

Of course, the method according to the invention is not restricted tothe use of brominechlorine methane (CH CIBr) or mixtures of CH 2 and CHCI For example, also mixtures of CHBr and CHCl, may be used, if requiredby adding hydrogen to the gas mixture. Mixtures of CHBr CI and CHBrCl orhigher hydrohaiogenic compounds or higher mixed halogen hydrocarboncompounds may also be used.

The invention will now be described in greater detail with' reference tothe ensuing specific examples in which reference is made to theaccompanying drawing the FIG. 1 of which diagrammatically shows thefilling (with transport gas) of the lamps according to the invention andFIG. 2 shows a filling cock.

FIG. 1 diagrammatically shows a device for filling incandescent lampswith gas. The device comprises in principle a storage cylinder 1 andpipes 2, 6 and 7. In the pipe 2 a reduction valve 3 and a filling cock-4are arranged. The pipe 2 communicates with a pipe 6 through a three-wayvalve 5 which pipe 6 serves for transporting the filling gas to theincandescent lamps to be filled and a pipe 7 which is connected to avacuum pump which is not shown and which serves for evacuating thesystem. in a practical example the pressure in the storage cylinder 1having a capacity of 8 litres initially was 24.6 atmosphere. The gasmixture consisted of krypton and 0.45 percent by volume of CH BrCl. Bymeans of the reduction valve 3 it is ensured that the pressure betweenthe reduction valve and the filling cock 4 remains constantly 1.2 latmosphere as long as the pressure in the storage cylinder has not[alien to said pressure. FIG. 2 diagrammatically shows a cross sectionof a filling cock 4. The filling cock consists in principle 0! a spindle8 in which a hollow space 9, capacity 2 cm.", is present the spindlebeing rotatable in a seating 8 a provided with two apertures 10 and 11which communicate with the pipes 2. The filling cock further comprises apipe 12 which communicates with a vacuum pump. As a result of this thespindle 8 cannot be released from the seating 8 a during filling.

By means of this cock 4 a dosed quantity of filling gas can beintroduced in the rest of the system. During filling the incandescentlamp the procedure is as follows (see also Fig. 2). The exhaust tube 13of the incandescent lamp 16 is made to communicate with the pipe 6. Thefilling system from the filling cock 4 up to and including theincandescent lamp are evacuated until the pressure is approximately lTorr. The pipe 7 is then closed by means of the three-way cock 5. Thefilling cock 4 is now rotated so that the space 9 communicates with theevacuated part of the system. Since the lamp 16 (capacity approximately0.25 cm.) is to be filled to a pressure of approximately 5 atmosphere atroom temperature, said lamp is placed in a vessel containing liquid air14. After a few seconds the exhaust tube is sealed immediately over thesurface of the liquid air 14 in the vessel 15 by means of a gas flame(not shown).

The lamp is now ready for use. 30.000 lamps can be filled from onestorage cylinder, taking the losses into account. At a pressure of 8.2atmosphere in the cylinder, as is maximally possible when using CH Bthis number is approximately 10.000 lamps.

It has been found that in incandescent lamps having a gas filling ofapproximately 1 atmosphere consisting of gas mixture of, for example,argon and CH,,Br or CH,BrCl, the CH,Br, may be replaced by a smallerquantity of cH BrCl.

In practical example, a photolamp of 1000 Watt at 225 Volt with a colortemperature of 3400 K. the gas filling consisting of 700 Torr Ar 8percent by volume of N,+l percent by volume of CH,Br, may be replaced by700 Torr Ar 8 percent by volume of N,+0.5 percent of CH BrCl. A lowerpartial halogen pressure built up from chlorine and bromine in the ratio1:1 thus is sufficient to maintain the cycle while the luminousefficiency of the lamp of approximately 32Lm/w. and the lifetime ofapproximately 30 hours are at least maintained.

Another advantage of the method according to the invention is thatcertain types of lamps can only be manufactured as a result of thismethod.

So far it was not possible to manufacture long cylindrical high loadedlamps for operation in a vertical position with a bromine-oriodine-containing filling has and a high rare gas pressure. In this typeof lamps gas separation occurred as a result of which the iodine orbromine concentration in the upper and lower part of the lamps differedstrongly after burning for some time. This had for its result that thelamp began to blacken at one of its filament ends by a local deficiencyof halogen while the other end of the filament was strongly attacked byan excess of atomic halogen. As a result of this lamps were obtainedhaving one black end and a comparatively short lifetime.

It has now been found that in such lamps the tungsten halogen cycle canbe maintained by chlorine and bromine together without blackening of thebulb and attack of the filament occuring. The good operation of the lampburning in a vertical position is ensured in spite of the demixing ofthe gas filling of the lamp. However, the demixing is such that thetungsten-halogen cycle on one side of the lamp mainly occurs betweentungsten and bromine and on the other side of the lamp space mainlybetween tungsten and chlorine.

In the center of the lamp both cycles occur.

What we claim is:

l. A regenerative cycle incandescent electric lamp comprising anenvelope, a tungsten filament, the distance from the filament body tothe wall of the envelope being so proportioned that the temperature ofthe wall of the envelope throughout the surface everywhere reaches atemperature at which tungsten-bromine chlorine compounds formed cannotcondense, and a mixture of brominated and chlorinated hydrocarbons andan inert has fillin%said envelope 2. A regenerative cycle mcan escentelectric lamp as claimed in claim 1 wherein the brominated andchlorinated hydrocarbons essentially consist of bromine and chlorinemethane compounds.

3. A regnenerative cycle incandescent electric lamp as claimed in claim1 wherein the brominated and chlorinated hydrocarbons essentiallyconsist of bromochloromethane (Cfl BrCl).

4. A regenerative cycle incandescent electric lamp as claimed in claim 1wherein the brominated and chlorinated hydrocarbons essentially consistof a further mixture of dibromomethane (CH Br and dichloromethane (CH ClUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 353.395 Dated June 22 1q7 Inventor(s) It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

q Column 2, line 35, change "11" to --l:l--

line 44, change "CI-1 2" to -CH Br Column 3, line 1 change "10 to --l0"Claim 1, line 30, change "has" to -gas- Siszned and sealed this 21 stday of December 1 971 (SEAL) fittest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer ActingCommissionerof Patents

2. A regenerative cycle incandescent electric lamp as claimed in claim 1wherein the brominated and chlorinated hydrocarbons essentially consistof bromine and chlorine methane compounds.
 3. A regnenerative cycleincandescent electric lamp as claimed in claim 1 wherein the brominatedand chlorinated hydrocarbons essentially consist of bromochloromethane(CH2BrC1).
 4. A regenerative cycle incandescent electric lamp as claimedin claim 1 wherein the brominated and chlorinated hydrocarbonsessentially consist of a further mixture of dibromomethane (CH2Br2) anddichloromethane (CH2C12).